The invention relates to a method of making components for laminated rubber products such as tires, and tire components and tires made by said method.
In the conventional method of making tires sized for use on passenger cars, light trucks and trucks, gum rubber plies and composite plies are laid up in sequence on a building drum and shaped into a tire. Prior to the building of the tire, reinforced composite plies such as carcass plies and belt plies are calendered to encase reinforcing cords in the ply rubber, and in some applications, belt packages are preassembled on a belt building drum. This procedure involves many interrelated steps and requires an inventory of each component and consequent warehousing of each component.
In addition, conventional preassembled tire components, by definition, have inherent boundaries, such as ply ends, belt edges, etc. that must be spliced, or in the case of belt edges, must be encased in rubber or other special components, to help prevent separation from other components in the tire.
It is a continuing goal in the art to reduce the number of steps in building a tire and to reduce the inventory of component parts that must be maintained. In the present invention this goal is accomplished, and in addition, carcass splices are eliminated, and in some embodiments belt edges are eliminated, as are additional components that are sometimes used to protect belt edges.
A method for building a pneumatic tire comprises the steps of (a) laying up tire components on a tire building drum up to the point before a carcass ply is laid down on the building drum, (b) pulling a full sock of seamless netting material over and in surrounding relationship to the drum and previously applied tire components, and (c) continuing to build a tire without the addition of a carcass ply. The method may further comprise the step of pulling additional layers of belt width socks of seamless netting material over the full sock and locating the belt width socks so as to form belts in a shaped tire.
The method may comprise the further additional step of preparing the seamless netting material by dipping the material in an adhesive.
The netting material may be prepared to have 5 to 40 epi cords or filaments in a nominal warp direction and 5 to 40 epi cords or filaments in a nominal weft direction.
The netting material may be selected from the group consisting of polyamide, aromatic polyamide, polyester, polyolefin, steel filaments, steel cords, brass coated steel cords or filaments, and mixtures thereof.
Also included in the invention is a pneumatic tire comprising at least a pair of parallel annular beads, a sock of seamless netting material wrapped around said beads, an unreinforced inner liner disposed radially inwardly of the seamless netting material, tread rubber disposed radially outward of the netting material in a crown area of the tire, and sidewalls disposed between the tread and the beads. Belt reinforcement may be disposed in the tire between the seamless netting material and the tread.
Also provided is a tire carcass comprising at least a pair of parallel annular beads, a sock of seamless netting material wrapped around the beads, an unreinforced inner liner disposed radially inwardly of the seamless netting material, gum rubber disposed radially outward of the netting material, and sidewalls disposed adjacent to the beads.
Also provided is a tire carcass comprising at least a pair of parallel annular beads, a sock of seamless netting material wrapped around the beads, an unreinforced inner liner disposed radially inwardly of the seamless netting material, gum rubber disposed radially outward of the netting material, tread rubber disposed over the gum rubber in a crown area of the tire, and sidewalls disposed between the crown area and the beads.
Also provided is a method for building a pneumatic tire comprising the steps of (a) placing an inner liner and other optional gum components on a tire building drum, (b) pulling a sock of seamless netting material over and in surrounding relationship to the drum and previously applied tire components, (c) covering or coating the seamless netting material with at least one additional layer of rubber, (d) setting beads over the additional rubber layer on the tire building drum, and (e) covering the beads and the additional rubber layer with at least one further layer of gum rubber to form a first stage carcass. The method may comprise the further step of adding tread rubber to said first stage carcass on the tire building drum.
Additional steps may include expanding said first stage carcass to contact a preformed belt package and tread or expanding the first stage carcass in a tire mold and curing a tire.
Also provided is a tubular netting material comprising interwoven or interlocked thermoset polymer filaments or cords wherein the netting forms a seamless woven structure having nominal warp and weft filaments wherein the filaments having a round, oblong, trapezoidal, flat cross section shape, wherein the filaments form at least one regular pattern in the tubular material throughout its length, and wherein said filaments/cords are coated with an adhesive material. In one embodiment the tubular netting material may have a greater number of nominal warp filaments than the number of nominal weft filaments.
Also provided is an apparatus for making tubular netting material comprising an extruder having a die with inner and outer counter rotating circular heads, orifices in said heads being shaped to provide robust filaments in at least one dimension when molten material is extruded through the heads, and means for varying the speed of rotation of the inner and outer heads. The apparatus may include means for coating filaments/cords of the netting with an adhesive and means for drawing the tubular material to elongate the tubular material 200% to 1000% along its primary axis.
Also provided is a method for forming a tubular material comprising the steps of (a) extruding a molten polymeric material through counter rotating inner and outer circular dies forming polymeric filaments which cross over each other in at least a portion of the extrusion, (b) cooling the filaments to thermoset the polymer and fuse cross over junctions between the filaments, and (c) drawing the tubular material to elongate the tube of netting material 200% to 1000% along its primary axis. The method may further comprise the step of coating the filaments with an adhesive before drawing said tubular material. The method may include the steps of obtaining dies with various orifice diameters and shapes, and changing dies based on the filament size and strength desired and varying the rotation speed of the inner and outer circular dies to be the same or different, faster or slower, or variable, depending on the extrusion pattern desired or stopping the rotation of said dies for a portion of said extrusion.
xe2x80x9cApexxe2x80x9d refers to an elastomeric wedge of material placed next to a bead to provide a smooth transition for a carcass ply turn up and to minimize flexing around the bead.
xe2x80x9cBeadxe2x80x9d means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim.
xe2x80x9cBeltxe2x80x9d refers to a layer of parallel reinforcing cords, woven or unwoven and embedded in an elastomeric material, unanchored to the bead, and when two or more belts are assembled into a xe2x80x9cBelt Packagexe2x80x9d or xe2x80x9cBelt Structurexe2x80x9d, the package or structure has cord angles of 17 to 27 degrees with respect to the equatorial plane of the tire.
xe2x80x9cBias Plyxe2x80x9d refers to a carcass with reinforcing cords extending diagonally from bead core to bead core at about 25 to 50 degrees with respect to the equatorial plane of the tire. When more than one carcass ply is used in a tire, reinforcement cords usually run at opposite angles in adjacent plies.
xe2x80x9cBuilding Drumxe2x80x9d refers to a cylindrical device on which shapeless material is applied (such as elastomeric tire components) to establish their relationship to one another and to make possible handling of the assembled components for shaping.
xe2x80x9cCarcassxe2x80x9d means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads.
xe2x80x9cChaferxe2x80x9d refers to a narrow strip of material placed around the outside of the bead to protect cord plies from the rim, distribute flexing above the rim, and to seal the tire with the rim.
xe2x80x9cCordxe2x80x9d refers to a plurality of filaments or yarns twisted together to form a single string or reinforcement element.
xe2x80x9cCrownxe2x80x9d refers to the circumferentially outermost portion of the carcass substantially within the width limits of the tread.
xe2x80x9cEquatorial plane (EP)xe2x80x9d means the plane perpendicular to the tire""s axis of rotation and passing through the center of its tread.
xe2x80x9cFilamentxe2x80x9d refers to a single strand or tow of yam. Sometimes referred to as a cord ply.
xe2x80x9cFirst Stage Carcassxe2x80x9d refers to a cylindrical carcass (non expanded) including all its component parts and standing alone apart from a tire.
xe2x80x9cSecond Stage Carcassxe2x80x9d refers to an expanded carcass including all of its component parts but standing alone from a tire.
xe2x80x9cInner Linerxe2x80x9d refers to a layer or layers of elastomer (usually halobutyl rubber) that form the inside surface of a tubeless tire and that contains the inflating fluid within the tire.
xe2x80x9cPantographingxe2x80x9d refers to the changing of the angles between reinforcement cords when a tire or carcass construction is expanded as it is shaped into a torus.
xe2x80x9cPneumatic tirexe2x80x9d means a laminated mechanical device of generally toroidal shape (usually an open-torus) having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire through its tread provides traction and contains the fluid that sustains the vehicle load.
xe2x80x9cRadialxe2x80x9d and xe2x80x9cradiallyxe2x80x9d are used to mean directions radially toward or away from the axis of rotation of the tire.
xe2x80x9cShoulderxe2x80x9d refers to the upper portion of sidewall just below the tread edge.
xe2x80x9cSidewallxe2x80x9d means that portion of a tire between the tread and the bead.
xe2x80x9cSplicexe2x80x9d refers to the overlapping or abutting of ply ends when the ply is deployed into a circular shape.
xe2x80x9cTreadxe2x80x9d means a molded rubber component which, when bonded to a tire casing, includes that portion of the tire that comes into contact with the road when the tire is normally inflated and under normal load.
xe2x80x9cTread widthxe2x80x9d means the arc length of the road contacting tread surface in the axial direction, that is., in a plane parallel to the axis of rotation of the tire.
xe2x80x9cTurn up plyxe2x80x9d refers to an end of a carcass ply that wraps around one bead only.
xe2x80x9cWedgexe2x80x9d refers to elastomeric material that is placed between the edges or above the edges of belts in a belt package to help flatten the crown area of the tire.